Community-acquired Complicated Urinary Tract Infections Caused by Escherichia coli: A Four-Year Retrospective Study in a Tertiary Care Hospital

INTRODUCTION: Urinary tract infections (UTIs) represent one of the most frequent infection-related reasons for outpatient encounters globally and are predominantly community-acquired, with Escherichia coli (E. coli) constituting the principal etiologic agent. Rising antimicrobial resistance in E. coli and the increasing frequency of complicated UTIs pose significant therapeutic challenges. This study aimed to determine the antimicrobial resistance profiles of E. coli isolates causing community-acquired UTIs in outpatients and to identify risk factors associated with the development of complicated UTIs.
METHODS: This retrospective study included adult patients who presented to a tertiary care hospital over a four-year period (between January 1, 2021, and December 31, 2024) with community-acquired UTIs caused by E. coli. Demographic characteristics, clinical features, comorbidities, microbiological data, and antimicrobial susceptibility results were reviewed. Antimicrobial resistance rates were calculated, and factors associated with complicated UTI were evaluated using univariate and multivariate logistic regression analyses.
RESULTS: A total of 414 patients were included, with a mean age of 49.7±18.3 years; 79.2% were female. The highest resistance rates of E. coli isolates were observed against ampicillin (51.9%), cefuroxime (37.7%), cefuroxime axetil (37.4%), and ciprofloxacin (33.6%). In multivariate logistic regression analysis, urolithiasis (Odds Ratio [OR]=2.67, 95% Confidence Interval [CI]=1.38–5.16, p=0.004) and the presence of a urinary catheter (OR=5.34, 95% CI=1.44–19.87, p=0.013) were identified as independent predictors of complicated UTI.
DISCUSSION AND CONCLUSION: High antimicrobial resistance rates emphasize the need for careful antimicrobial stewardship in community-acquired complicated UTIs. Our findings suggest that empirical use of fluoroquinolones may be inappropriate in this setting and that commonly preferred cephalosporins and ciprofloxacin should be used with caution. In addition, targeted evaluation and management of urolithiasis and routine reassessment of urinary catheter necessity may help reduce the burden of complicated UTIs.

Keywords: Antibiotic resistance, Escherichia coli, urinary catheter, urinary tract infections, urolithiasis.